An estimated 18,000 people attended the one-day Get Motivated seminar, which included presentations from Colin Powell, Tony Dungy, Rudy Giuliani and others. Doors opened at 6:45 a.m. for the 8 a.m. to 4:45 p.m. event.

Mike Scanlon, a Tampa traffic design engineer, said that many people will likely leave the event early, and afternoon rush hour won't be as much of a headache.

The biggest backups could be in the parking lots and garages instead of on the roads, Scanlon added.

It'll be worse than a normal day's rush hour, but certainly not like the morning.

Interstate 275 was backed up at every exit into downtown, especially N Tampa and Ashley streets. Tampa-bound traffic was backed up all the way over the Howard Frankland Bridge into Pinellas County.

The city advised motorists westbound on Interstate 4 to take the Ybor City exit because downtown exits were backed up.

Traffic cops were stationed at nearly every corner to direct pedestrians and motorists. A police helicopter flew overhead with city traffic engineers onboard monitoring the snarls below.